LTE (Long Term Evolution) system is the evolution of 3G (3rd Generation, the third generation communication technology) technology, it has progresses in system performance requirements, network deployment scenarios, network architecture and service support capabilities and so on, compared to 3G technology.
In LTE system, the maximum power which base station equipment allocated to the user equipment through the UL grant can not exceed the maximum transmitting power of the user equipment in the carrier. In order to feedback the current transmitting power of user equipment to base station, and facilitate the base station equipment configuring and scheduling in time, the user equipment has to report PH (Power Headroom) message. The reporting process is called PHR (Power Headroom Reporting). Therein, PH value is the difference between the maximum transmitting power of user equipment and the transmitting power of PUSCH (Physical Uplink Shared Channel), which user equipment estimated. The PH value can be calculated according to the following formula:PH=PMAX−PPUSCH;
Therein, PH is power headroom, PMAX is the maximum transmitting power of user equipment, and PPUSCH is the power used for transmitting PUSCH which carrying PHR message.
PHR reporting format includes a MAC (Media Access Control) subheader and a MAC CE (Control Element), respectively, as shown in FIG. 1 and FIG. 2.
Therein, LCID (Logical Channel ID) is used for identifying some of the logical channel number corresponding to the load, for reporting PHR, LCID is used for identifying the corresponding load as PHR; E is extension bit, which is used for identifying next byte that is MAC subheader or MAC load; R is reserved bit; PH is power headroom.
PHR-related parameters including the period of periodic PHR-Timer, length of prohibit PHR-Timer and the dl-Pathloss Change parameters for triggering PHR, above parameters are configured by RRC (Radio resource control) layer. PHR configuration parameters, as following:
phr-ConfigCHOICE {releaseNULL,setupSEQUENCE {periodicPHR-TimerENUMERATED {sf10, sf20, sf50, sf100,sf200,sf500, sf1000, infinity},//description: sf10 indicating the period of periodicPHR-Timer is 10 sub-frame,the meaning of other parameters and so on.prohibitPHR-TimerENUMERATED {sf0, sf10, sf20, sf50,sf100,sf200,sf500, sf1000},//description: sf10 indicating the period of prohibitPHR-Timeris 10 sub-frame,the meaning of other parameters and so on.dl-PathlossChangeENUMERATED {dB1, dB3, dB6, infinity}//description: dB1 indicating the value of dl-PathlossChangeis 1 dB, themeaning of other parameters and so on.}
Corresponding with the PHR-related parameter, the trigger conditions comprising:
1. Uplink resources in said user equipment is available, prohibitPHR-Timer expires, and the pathloss changes from the most recent PHR over dl-PathlossChange dB;
2. periodicPHR-Timer expires;
3. high layers configure PHR initially or re-configures PHR.
When any of the above condition is satisfied, user equipment triggers PHR, informs physical layer to calculate PH value, and informs Multiplexing and
Assembly process to generate PHR MAC CE; Start/re-start periodicPHR-Timer and prohibitPHR-Timer; cancels all PHR triggered.
However, in the LTE system applying to said PHR mechanism, there is one carrier in a cell, and the cell is called signal-carrier cell. According to LTE system protocol, the maximum bandwidth which can be transmitted is 20 MHz in signal-carrier cell, and the lower bandwidth can not fully meet the increasing user demand for high transmission rates. Based on the above, generating the LTE-A (LTE-Advanced, Advanced Long Term Evolution) system in communications technology field. Peak speed of the system has greatly improved over LTE, and the downlink speed is up to 1 Gbps, the uplink speed is up to 500 Mbps. Furthermore, LTE-A system with LTE system also has good compatibility.
In course of implementing the present invention, the inventor finds out there are at least the problems below in the present technology:
In the present technology, the PHR mechanism only applies to signal-carrier system, it can not apply to multi-carrier system as LTE-A, and it leads to user equipment in multi-carrier system can not report power headroom, and base station equipment can not uplink scheduling according to the power headroom user equipment reported.